John Smith wrote:
On which, I respond; "Why would the mere length/phasing of elements on
an antenna be able to cause one to act as a mirror (the one longer than
DE) and the other as a director (the one shorter than DE)?

It has to do with the phasing of the photons and the
spacing of the elements. The phasing+spacing results
in constructive interference in the direction of the
director and destructive interference in the direction
of the reflector referenced to the driven element. The
length of the element affects (and effects) the phase
of the re-radiated signals from the parasitic elements.

Using EZNEC with two identical driven elements, one
can control the direction of maximum radiation simply
by adjusting the phasing of one of the driven elements
referenced to the other. Reversing the phasing reverses
the direction of maximum radiation.
--
73, Cecil http://www.w5dxp.com